An Efficient Hierarchical Approach for Synthesis of Multi-Stage Wide-Band Amplifiers

This paper proposes an efficient approach for hierarchical synthesis of multi-stage wide-band amplifiers. The proposed technique follows a bottom up design scheme. At the bottom level, a multi-objective algorithm (SPEA-2) is employed to obtain the Pareto-optimal front (POF) of a single-stage wide-band amplifier. Then, the obtained Pareto-optimal points (POPs) are combined one by one to constitute the POFs at the higher levels. Finally, we extract the final POF from the obtained POPs by using the SPEA-2 selection procedure. Once the POF of a two-stage amplifier is obtained, this circuit is encapsulated as an single amplifier by itself in order to construct the further stages in the hierarchy. Synthesis results have indicated that a flat optimization approach for a three-stage wide-band amplifier requires about 4.5 times the number of iterations compared to the proposed approach for a similar POF, with each iteration requiring a much longer simulation time as well.